Measure the icing sugar and lemon juice accurately.
Place the icing sugar in a bowl. Gradually add the 8 tablespoons lemon juice, whisking until smooth and lump-free. A whisk works best for creating a smooth glaze.
Carefully spoon the lemon glaze over the cake. Use a knife or small spatula to spread the glaze evenly over the surface.
Remove any excess glaze that has dripped onto the serving plate.
Finish the cake with fresh lemon slices and flowers.